Known variable force suspension systems include variable force shock absorbers and/or struts that provide suspension damping forces at a magnitude controllable in response to commands provided by a suspension system controller. Some systems provide control between two damping states and others provide continuously variable control of damping force.
In a known manner of control of a variable force suspension, the demand force for each variable force damper is determined responsive to a set of gains, the wheel vertical velocity and the body heave, roll and pitch velocities. An example system determines the demand force as follows: EQU DF.sub.b =G.sub.h H'+G.sub.r R'+G.sub.p P'+G.sub.w v,
where DF.sub.b is the demand force, G.sub.h is the heave gain, G.sub.r is the roll gain, G.sub.p is the pitch gain, G.sub.w is the wheel velocity gain, H' is the body heave velocity, R' is the body roll velocity, P' is the body pitch velocity and v is the wheel vertical velocity. The portion of the demand force computation, G.sub.h H'+G.sub.r R'+G.sub.p P', represents the body component determined responsive to the body heave, roll and pitch velocities and the portion of the demand force computation G.sub.w v represents the wheel component determined responsive to the difference between the computed body comer velocity and the body-wheel relative velocity.
A control signal representing the determined demand force is output to control the variable force damper responsive to the demand force. Example systems are described in U.S. Pat. Nos. 5,235,529, 5,096219, 5,071,157, 5,062,657, 5,062,658, all assigned to the assignee of this invention.